Trisomy 21, Mosaic Down Syndrome or Mongolism are two types of Down Syndrome. Where do I find out information about this disability and receive help if needed when my child has Down's? . Most cases of Down Syndrome are caused by and extra 21 chromosome and Mosaic is when only part of the cells have an extra 21st chromosomes. The following are some of the characteristics of Down Syndrome children: A. Flattened nose B. Protruding tongue C. Upward slanted eyes D. Short hands with broad palms with short fingers E. Single palmar crease on the palm F. Shorter then average adult height G. Average mental age of 8 years old These web sites will help a person interested in Down Syndrome locate the type of information needed to understand Down Syndrome. These Down Syndrome sites can give important knowledge to parents and teachers of Down's children so that they can meet these children’s needs.